There are many different types of plastic forming devices including molding devices, extruder dies, extruder die tooling, injectors, etc.etc. These devices can be used to form thick plastic parts or they can be used to make products as thin as plastic film or the like. Typically these devices will have some type of a plastic flow channel which has a gap that is adjustable according the amount of plastic material desired to be flowed through the channel. However, for most of these devices, it is a complicated and time consuming effort to make the adjustment which generally requires shut down and disassembly of the components to make the gap adjustment.
One particular example of a plastic forming device is a die for the extrusion of plastic pipes which may be single walled, double walled, smooth walled or ribbed walled. PVC or polyvinylchloride is a preferred material for pipe construction. However, PVC is a material that can present potentially problems within a pipe die if the die is not set up properly.
More particularly, pipe dies have an adjustable gap extrusion channel with a part of the die which lies along one side of the channel being adjustable axially of the die to vary the gap of the channel. The movable part is mounted on a support for the part and it is extremely important that there by a tight fit between the part and its mount to ensure that PVC does not get trapped between the two parts where it would quickly degrade and result in potential problems such as burnouts and the like.
The conventional method of mounting an adjustable channel guide in a pipe die is by means of a mechanical interlock internally of the die. In order to make the channel gap adjustment with this type of an interlock requires a major internal disassembly of the components which then must be reassembled with one another or replaced with different parts to make the adjustment. This requires that the die be shut down for a job that might take a day or two. The die is then restarred and if the adjustment made is not satisfactory, then the whole process of disassembling and reassembling must be repeated until the correct adjustment has been made.